The present invention relates to an upper vehicle-body structure of a vehicle, and specifically to an upper vehicle-body structure of a vehicle which comprises a pair of right-and-left roof rails provided at right-and-left both end portions of a roof portion of the vehicle and extending in a vehicle longitudinal direction, a roof panel provided between the pair of right-and-left roof rails, a roof reinforcement extending in the vehicle width direction below the roof panel, and a center pillar extending vertically at a side portion of a vehicle body.
Conventionally, the following structure is known as the above-described upper vehicle-body structure of a vehicle. That is, that is a front vehicle-body structure of a vehicle comprising a pair of right-and-left roof rails provided at right-and-left both end portions of a roof portion of the vehicle and extending in a vehicle longitudinal direction, the roof rail having a panel joint portion (a so-called Mohican portion) having a recess-shaped cross section where plural panels are overlapped vertically and joined together at an inward end portion, in a vehicle width direction, of the roof rail, a roof panel provided between the pair of right-and-left roof rails, a roof reinforcement extending in the vehicle width direction below the roof panel, a center pillar, an upper portion of which is joined to the roof rail at a position which overlaps the roof reinforcement in the vehicle longitudinal direction, the center pillar extending downward from the upper portion thereof, and a gusset joined to an end portion, in the vehicle width direction, of the roof reinforcement.
In the above-described conventional structure, since a side-collision load is inputted to the center pillar in a vehicle side collision, a torsional load is transmitted from the center pillar to the roof rail. Herein, since the above-described panel joint portion (Mohican portion) is not a structure having a closed cross section, the spot welding of the panel joint portion may get broken, thereby the section of the roof rail may crush, so that a moment occurring at this time may cause bucking of a portion of the roof reinforcement which is located in the vicinity of a roof side. Consequently, there is a concern that the center pillar may improperly come into a vehicle compartment greatly. Herein, it may be considered that the thickness of the center pillar is designed to be thicker or a reinforcing member is additionally provided in order to restrain the center pillar from coming into the vehicle compartment. In this case, however, there is a problem in that the weight of the vehicle body may become heavy.
An upper vehicle-body structure of a vehicle disclosed in Japanese Patent Laid-Open Publication No. 2009-67328 has been invented to solve the above-described problem. The structure disclosed in the above-described patent document comprises a roof rail extending in the vehicle longitudinal direction and having a closed cross section formed by a roof rail outer and a roof rail inner, a roof reinforcement extending in the vehicle width direction below a roof panel, and a gusset connecting an inward end portion, in the vehicle width direction, of the roof reinforcement and the roof rail inner, wherein a step portion is formed at a central portion, in the vehicle width direction, of the gusset so that a stress can be focused on the step portion in a vehicle side collision so as to bend the gusset around at the step portion. Thereby, the bending moment transmitted to the roof reinforcement may be decreased properly. However, the decrease of the bending moment may not be sufficient yet, so there is a room to make improvements.